The forum isn't based in the US.
Irrelevant. International criminals can have warrants waiting for them if they ever choose to enter the country, and if you are in a country with an extradition treaty with the US, depending on the severity of those emails, you won't have to choose.
If you're in Canada, you're hosed (seewhatIdidthere?) as US courts will happily entertain criminal and civil cases against Canucks.
US courts don't really care about jurisdiction, especially if there is racketeering or conspiracy involved.
So who's going to start off all these racketeering and IRS investigations by reporting pirate's scheme (and possibly GPUMax) to the relevant authorities? There might be a lot of people who want pirate's dealings put under a microscope, but not at the risk of their own financial affairs being subjected to scrutiny.